Not Applicable
Not Applicable
Not Applicable
The present invention relates to valves disposed on a vehicle fuel tank for controlling the flow of fuel vapor from the vapor dome within the tank to a reservoir or storage canister for storing fuel vapor during periods of engine shutdown.
Fuel tank vapor vent valves are typically mounted through an access hole in the top of the fuel tank and sealed thereon and have a float in the valve which is calibrated to close the vent orifice in the valve when the liquid fuel level reaches a predetermined level in the tank.
As the fuel level is lowered by withdrawal of fuel from the tank for engine operation, a float is permitted to drop a desired amount to open the vent passage. In this condition, sloshing of the fuel due to vehicle motion can cause the float to be moved downward with a sufficient velocity to impact the limit stop or bottom of the float casing thereby producing sounds which are perceptible to the vehicle occupants. The noise from the rattling or bouncing of the float against its lower limit stop is considered to be annoying and unacceptable.
Attempts to provide frictional dampening of the movement of the float have generally been unsuccessful in that the buoyancy forces acting on the float are relatively low; and, any friction force on the float results in delayed closing of the float and improper operation of the valve.
Thus, it has long been desired to find a way or means for quieting the movement of the float in a fuel tank vapor valve without interfering with the operation of the valve or significantly increasing the manufacturing cost of the valve.
The present invention provides a float type valve for controlling venting the fuel vapor in a fuel tank. The valve of the present invention addresses the above-described problem of silencing the float from rattling or hitting against its lower limit stop due to fuel sloshing or vehicle motion when the fuel level is sufficiently low to permit the float to drop to a fully open position.
The valve of the present invention has the limit stop provided with resilient fingers which are engaged by a tapered surface on the float. As the float drops, it contacts and resiliently deflects the fingers, which deflection decelerates the float and provides the limit stop. This construction results in an increased time for decelerating the float for a given velocity and thus reduces or eliminates any noise which would be generated by the float otherwise suddenly engaging its limit stop.